The present invention is directed to a high pressure sample injector valve and, more particularly, is directed to an injector valve that is used in an analyzer system such as in an amino acid analyzer which uses ion exchange liquid column chromatography.
In presently used systems such as in liquid chromatography it is extremely important that the sample which is being injected into the column not be mixed or diluted with any other type of material or liquid. It should only contact a buffer which will separate it from other samples and provide a border between various samples being injected into the system. However, it is also important that, after each sample is injected into the liquid column, the entire sample injection system be washed with some type of rinse solution in order that no impurities or sample carryover will be imparted into the next sample to be injected into the system and into the column.
However, the washing process, although eliminating the contamination which may occur by any residual portion of the previous sample being within the system, creates an additional problem with respect to the existence of some of the rinse solution remaining in the valve after the washing cycle. Consequently, when the next sample is injected through the valve, some of the rinse solution may be carried by the sample into the liquid column, causing a possible mixing and/or diluting of the sample and resulting in a degradation of the analysis to be accomplished in the liquid column chromatography.
Also, since the valving arrangement is for use in a high pressure system, some type of arcuate or rotative motion is imparted into the valving member to cause it to assume its proper position between either an inject or a bypass position. However, many of the presently used valves in such a system require a relatively large arcuate rotation of approximately sixty to ninety degrees. This rather large arcuate movement will cause significant wear on the sliding surfaces used in most valve construction due to the high loading forces that are necessary in the operation of a high pressure sample injector valve. Also, the need for a large arcuate movement in the valve will require rather complex and expensive linkages occupying significant space to accomplish the necessary movement.